To assess the performance of a number of processes in which urea is gasified by a thermal process, it is necessary to have the ability to determine how much of a feed of urea stream is being properly gasified at any time. The economic and efficient control of on-demand supply of ammonia and/or isocyanic acid requires accurate conversion data. However, there is no known analytical device that will enable the real-time analysis urea conversion products in a gas stream following a thermal conversion reactor.
There are a number of references that discuss converting urea to ammonia. Principal among these, from the inventors standpoint are high-temperature processes such as U.S. Pat. No. 7,090,810 to Sun, et al, which describes a thermal process that can produce complex product gas streams that makes control more complex than would be desired.
When aqueous urea is heated, a number of chemical reactions, controlled by temperature-dependent rate constants, determine how urea is broken down:
This reaction can occur at a temperature of 275° F.; however, it is not possible to determine the amounts of either the ammonia or the isocyanic acid because the HNCO can be hydrolyzed to urea or form solid byproducts. The HNCO can be converted as follows:
Cyanuric acid, if formed, decomposes at about 700° F. The full conversion of urea to ammonia can involve the following reactions:
These reactions are rate dependent as well as dependent on the physical form of the reactants, the prevailing temperature, the time in the reactor and the presence or absence of water and/or a catalyst. Thus, the gas stream following a thermal conversion reactor is very complex. Not all of these are desirable and real-time quantitative measurement techniques are not available.
There is a present need for a process, apparatus and system that will enable the real-time analysis urea conversion products in a gas stream following a thermal conversion reactor.